The rock layers below the seafloor will be water saturated and contain ions making the rocks electrically conductive, thus that provide high conductivity or low resistivity, ρ=0.7 to 3 Ωm. in this specification we will use the term resistivity, expressed in Ohm-meter abbreviated Ωm. Petroleum in the form of oil or gas displaces water in pore spaces of such petroleum bearing rock layers. Petroleum does not dissolve salts and is thus a weak electrical conductor, thus petroleum bearing rock layers provides a high resistivity, ρ=20 to 200 Ωm, and in some instances having a resistivity as high as 1000 Ωm. Sea water contains many different dissolved salts and usually has a resistivity of about 0.3 Ωm.